login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A062239 Numbers n with property that every digit is a prime factor of n. 2
2, 3, 5, 7, 22, 33, 55, 77, 222, 333, 555, 735, 777, 2222, 2232, 2322, 2772, 3222, 3333, 3555, 5355, 5535, 5555, 5775, 7777, 22222, 22332, 22722, 23232, 23322, 23772, 27272, 32232, 32322, 33222, 33333, 33555, 35355, 35535, 37737, 53355, 53535 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is a regular language in base 10. Almost all members of this sequence are multiples of either 42 or 105. There are about 2/63 * 3^n members of this sequence up to 10^n. - Charles R Greathouse IV, Nov 09 2011

LINKS

Harry J. Smith and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 1000 terms from Smith)

EXAMPLE

77322 is divisible by 7, 3 and 2.

MATHEMATICA

Select[Range[2, 50000], Complement[IntegerDigits[#], FactorInteger[#][[All, 1]]] == {} &] (* Alonso del Arte, Dec 05 2011 *)

PROG

(PARI) { n=0; for (m=1, 10^10, t=m; b=1; while (t>0, d=t%10; t=(t-d)/10; if (!isprime(d) || m%d, b=0; break)); if (b, write("b062239.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 17 2010

CROSSREFS

Sequence in context: A062087 A162457 A084983 * A066483 A114420 A113590

Adjacent sequences:  A062236 A062237 A062238 * A062240 A062241 A062242

KEYWORD

base,easy,nonn

AUTHOR

Erich Friedman, Jun 30 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 25 19:53 EDT 2017. Contains 288729 sequences.